1. Field of the Invention
The present invention relates to a power transmission chain and a power transmission system provided with the chain.
2. Related Art
An endless power transmission chain to be used in a power transmission system such as a pulley type continuously variable transmission (CVT) of an automobile is provided with a plurality of links, and pins connecting those links, so that the paired end faces of the pins individually engage with the taper disks of pulleys thereby to transmit the power between themselves and the pulleys (as referred to JP-A-2005-214323 and JP-A-2005-214345, for example).
In the power transmission chain of JP-A-2005-214323, with the links being superposed in the thickness direction, pins are press-fitted in the pinholes of those links, and the links arranged to adjoin each other are bendably connected to each other. These adjoining links make frictional contact at their side faces with each other. These side faces of the links are covered with such a coating material as can be worn or peeled as the chain is used. As the coating material is worn or peeled, the contacting facial pressure between the side faces is lowered to reduce the bending torque at the bending time.
In the power transmission chain of JP-A-2005-214345, clearances are formed between the links adjoining in the chain width directions so that the links may not come into frictional contact. As a result, the bending torque at the bending time is reduced.
The aforementioned power transmission chain can effectively suppress the chord vibrations, which might otherwise be made in the chain radial direction in the areas in front of and at the back of the pins are bitten into the pulleys. However, the chord vibrations may occur according to the moving conditions. In this case, the pins are impulsively brought into contact with the pulleys to cause noises or the wears of pin end faces undesirably. Especially if the frequency of the chord vibrations coincides with the natural frequency of the power transmission chain, the amplitude becomes undesirably large.
In JP-A-2005-214323 and JP-A-2005-214345, however, the bending torque of the power transmission chain is reduced to have a low resistance to the damping of the chord vibrations so that the chord vibrations are hard to suppress once they occur. It is conceivable to attenuate the chord vibrations of the power transmission chain by the contact frictions caused when the links adjoining in the chain width directions are brought into contact. If the links are merely brought into the frictional contact, however, the loss at the bending time is increased to drop the transmission efficiency drastically.
The present invention has been conceived on the background thus far described, and has an object to provide a power transmission chain excellent in a vibration suppressing effect and satisfactory in transmission efficiency, and a power transmission system provided with that power transmission chain.